Colorado still working on THC DUI limits

In the past we’ve written about Colorado’s efforts to set a clear standard for determining impairment in cases of driving while impaired by marijuana. In November Colorado passed Amendment 64, which made it legal for adults over the age of 21 to buy, possess and use limited quantities of marijuana. Some believe that legalizing the recreational use of the drug would lead to more cases of stoned driving.

Colorado has tried and failed to pass such legislation several times, in part because there are several complicating factors. Everyone’s body reacts to marijuana differently, much like alcohol, so it is difficult to determine a limit that can point to impairment. In addition, THC tends to stay in a prison’s body for quite some time after use, perhaps after the effects have worn off.

In addition, Colorado already has a DUI law that addresses impairment by any controlled substance, including marijuana. Some law enforcement officials worry that passing a new law specifically for marijuana will complicate things and make it harder to prosecute and defend cases of impaired driving.

Past versions of the bill, which failed, set a hard legal limit of 5 nanograms of THC per milliliter of blood in order to operate a motor vehicle. Anything more would essentially act as proof that a driver was impaired. This standard received a lot of backlash from those who argued that impairment is more nuanced than a simple number, especially in light of some the issues discussed above.

The newest version of the bill keeps that limit of nanograms per milliliter but also allows suspects in impaired driving cases to present evidence that they were not actually impaired. For example, if a defendant could show that he or she did not use marijuana for several hours or even days before the traffic stop, he or she would likely be found not guilty even with a THC level above the limit.